Look at what the US has done. Really, look at all the things it has done -- the surveillance, the drone strikes, the infiltration of civil protests, the use of military equipment by the police force, the lies to justify the war in Iraq, the lies to justify the torture, the violations of international human rights, the targeted killings of "enemy" US citizens, the re-definition of every single one of these words -- and then tell me how the US has upheld its values against terrorism.
Then look at countries like Iceland where the nation apologizes over a single justified death at the hands of a police officer, or Norway where after a killing spree and bomb attacks the first consideration by government officials is not about how to punish the murderer, but how to guarantee due process for someone evidently guilty of such heinous crimes.
The United States are not the good guys. I'm sorry, but you're not. No matter how much you want it to be true.
There isn't even any evidence that the threat of nuclear terrorism is credible. Nukes aren't something you pick up at the local Safeway on your way home from the daily jihad. Compare to 30 years ago, where the threat was absolutely, 100% credible. Literally hundreds of missiles ready to go at a moment's notice. One bad decision or bad hangover away from a billion deaths. And yet, we weren't having debates like this then.
That's not to say that the US was all innocent and pure. But at the very least, torture was secretive, hidden, not defended in public as being a worthwhile and justifiable act.
And then combine all that with the simple fact that torture doesn't even work. All it does is make their friends angry. Do you really think that torturing suspected terrorists reduces the chances of a future terrorist nuclear detonation in Manhattan? I don't see how.
Edit: Oh yeah, I forgot to point out that those hundreds of missiles and hundreds of nuclear warheads are still there and still ready to go at a moment's notice and we are still one person's bad decision or bad hangover away from total annihilation. We just manage to pretend it's not there.
Great question, and one we should always keep in mind. The death toll from terrorism on US soil since 9/11 is indeed very low. That said, the people plotting against us are intelligent and adaptive and wish to do us harm. If they succeed, they might destroy the free society which we've built for ourselves.
Put another way, I'm scared of the physical consequences of a nuclear weapon going off in midtown Manhattan and even more scared of what would happen to our society in the wake of it. You think we'd be having these conversations about which techniques may or may not be torture if there were half a million dead in NYC and the entire tri-state region were irradiated?